MEMORANDUM 

 TO: Bill Swietlik, EPA 

FROM: Jill Lucy, ERG 

 

DATE: April 19, 2013 

SUBJECT: Fish Consumption Rate for Cohorts for the Steam Electric ELGs 

Environmental Assessment (DCN SE01963) 

 The U.S. Environmental Protection Agency (EPA) is proposing revised effluent 

limitations guidelines and standards (ELGs) for the Steam Electric Power Generating Point 

Source Category (40 CFR 423). In support of the development of the revised ELGs, ERG 

supported EPA in conducting an environmental assessment (EA) to evaluate the potential 

environmental and human health impacts of pollutant loadings released under current (i.e., 

baseline) discharge practices and assess the potential improvement from pollutant loading 

reductions under varying regulatory options. 

EPA developed a receiving water model to quantify the impacts to surface waters, 

wildlife, and human health from the waste streams evaluated for the EA (i.e., fly ash transport 

water, bottom ash transport water, flue gas desulfurization (FGD) wastewater, and landfill and 

surface impoundment leachate). The receiving water model calculates the bioaccumulation of 

pollutants1

 in fish tissue for trophic level three (T3) or trophic level four (T4)2 fish, using the 

model-calculated pollutant concentration in the water column and a pollutant-specific 

bioconcentration factor (BCF). For mercury, the model calculates the concentration of 

methylmercury in the fish.3 Using the calculated T3 and T4 fish tissue concentrations, the model 

estimates the daily contaminant (i.e., metal) doses for human receptors as a result of eating T3 

and T4 contaminated fish. Using the daily doses, the model evaluates the cancer risk and 

potential to cause non-cancer health effects from the consumption of fish within the following 

age and consumption categories: 

 Child recreational fishers; 

 

1 EPA included ten pollutants in the receiving water model: arsenic, cadmium, copper, chromium VI, lead, mercury, 

nickel, selenium, thallium, and zinc. 

2

 T3 fish (e.g., carp, smelt, perch, catfish, sucker, bullhead, sauger) are those that consume invertebrates and 

plankton, while T4 fish (e.g., salmon, trout, walleye, bass) are those that consume other fish. 

3

 “(E)lemental mercury isn’t expected to deposit significantly onto soils and surface water. Therefore, it’s assumed 

that there is no transfer of elemental mercury into fish. Fish are assumed to be exposed only to the divalent and 

organic forms of mercury that exist in the water and soil/sediment media. However, as with the conservative 

approach adopted by previous guidance documents, all of mercury in the fish is assumed to exist or be converted to 

the methyl mercury (organic) form after uptake into the fish tissue” [U.S. EPA, 2005. Human Health Risk 

Assessment Protocol for Hazardous Waste Combustion Facilities (HHRAP). EPA 520-R-05-006. Washington, DC. 

(September).[DCN SE01926]. 
 Child subsistence fishers;

 Adult recreational fishers; and 

 Adult subsistence fishers. 

This memorandum documents the development of fish consumption rates used for human 

receptors (cohorts) in the receiving water model. EPA’s Environmental Assessment for the 

Proposed Effluent Limitations Guidelines and Standards for the Steam Electric Power 

Generating Point Source Category (EA Report) (DCN SE01995) provides more detailed 

information on the receiving water model, including the water quality, wildlife, and human 

health portions of the model (see section 4.1.2 and Appendices C, D, and E). 

1.0 DESCRIPTION OF HUMAN COHORTS IN THE RECEIVING WATER MODEL

 EPA’s assessment of the potential human health impacts from steam electric plant 

discharges involved defining specific human cohorts based on the exposed individual’s age and 

fishing frequency (recreational vs. subsistence)4

. The receiving water model included the 

following 14 cohorts: 

 Recreational fishers 

o Adult 

o Child, age 1 to < 2 years 

o Child, age 2 to < 3 years 

o Child, age 3 to < 6 years 

o Child, age 6 to < 11 years 

o Child, age 11 to < 16 years 

o Child, age 16 to < 21 years 

 Subsistence fishers 

o Adult 

o Child, age 1 to < 2 years 

o Child, age 2 to < 3 years 

o Child, age 3 to < 6 years 

o Child, age 6 to < 11 years 

o Child, age 11 to < 16 years 

o Child, age 16 to < 21 years 

The child cohort age ranges correspond to the ranges provided for body weights in U.S. EPA 

2008 Child-Specific Exposure Factor Handbook [EPA/600/R-06/096F], Washington, DC. 

(September) [DCN SE01876]. 

 

4

 “Subsistence fishermen are those individuals who consume fresh caught fish as a major source of food. Their 

intake rates are generally higher than those of the general population.” Reference: U.S. EPA Exposure Factors 

Handbook: 2011 Edition (EPA/600/R-09/052F), National Center for Environmental Assessment and Office of 

Research and Development (September) [DCN SE01912].
Memorandum 

April 19, 2013 

Page 3 

 To determine the average daily pollutant doses from fish consumption, EPA needed the 

following information that did not depend on the specific cohort: 

 Concentration of pollutant in fish (T3 and T4) – calculated in the receiving water model. 

 Fraction of consumed fish that are classified as T3 or as T4 – calculated value based on 

data provided in U.S. EPA Exposure Factors Handbook: 2011 Edition [EPA/600/R09/052F], Washington, DC. (September) [DCN SE01912]. See Appendix E of the EA 

Report. 

 To determine the average daily pollutant doses from fish consumption, EPA needed the 

following information that did depend on the specific cohort: 

 Body weight of cohort – literature sources used include U.S. EPA 2008 Child-Specific 

Exposure Factor Handbook [EPA/600/R-06/096F], Washington, DC. (September) [DCN 

SE01876] for child cohort body weights and U.S. EPA Exposure Factors Handbook: 

2011 Edition [EPA/600/R-09/052F], National Center for Environmental Assessment and 

Office of Research and Development (September) [DCN SE01912] for adult body 

weights. 

 Consumption rate of cohort – see Section 2 of this memorandum. 

2.0 ESTIMATING THE CONSUMPTION RATE FOR HUMAN COHORTS

 Table 2-1 presents the cohort specific input values used in the receiving water model. 

Section 1 of this memorandum explains the cohorts listed and the source of the cohort body 

weights. The development of the consumption rate values is described after the table. 

Table 2-1. Cohort-Specific Input Values for the Receiving Water Model 

Receptor Cohort 

Body Weight 

(kg) 

Consumption Rate 

(g/day) 

Child Recreational Fisher 1 to <2 years 11.4 2.5 

2 to <3 years 13.8 3 

3 to <6 years 18.6 3.5 

6 to <11 years 31.8 5.1 

11 to <16 years 56.8 5.7 

16 to <21 years 71.6 7.2 

Child Subsistence Fisher 1 to <2 years 11.4 13.7 

2 to <3 years 13.8 16.6 

3 to <6 years 18.6 26 

6 to <11 years 31.8 35 

 11 to <16 years 56.8 39.8 

16 to <21 years 71.6 50.1 

Adult Recreational Fisher 80 20 

Adult Subsistence Fisher 80 88 

Acronyms: kg (kilograms); g/day (grams per day). 
Memorandum 

April 19, 2013 

Page 4 

 To determine the consumption rates for use in the receiving water model, EPA used data 

documented in the U.S. EPA Exposure Factors Handbook: 2011 Edition (EPA/600/R-09/052F) 

[DCN SE01912]. The fish intake rates provided in the handbook are recommended for the 

general population; however, the handbook notes that the selection of consumption rates for 

exposure assessment purposes may vary depending on the exposure scenarios being evaluated. 

To be consistent with other data used in the EA Report, EPA used the mean consumption rate 

values where available. Data were also available for the 95th percentile values, representing the 

most conservative (highest) fish consumption rate values. However, the use of the 95th percentile 

values may not be appropriate for a national-scale assessment. Mean values were available for 

adult recreational fishers and adult subsistence fishers. 

 For child cohorts, EPA identified consumption rates for the general population, but did 

not find consumption rates specific to subsistence fishers. EPA used the mean values provided in 

the U.S. EPA Exposure Factors Handbook: 2011 Edition (EPA/600/R-09/052F) [DCN SE01912] 

for child recreational cohorts. As defined in the handbook, subsistence fishers are those 

individuals who consume fresh caught fish as a major source of food and their intake rates are 

generally higher than those of the general population. Therefore, ERG used best professional 

judgment to select the 95th percentile consumption rates for the general population to represent 

consumption rates for child subsistence cohorts. 

Child Cohorts – Recreational and Subsistence Fishers 

 EPA determined consumption rates for child cohorts using data in Table 10-1 of the U.S. 

EPA Exposure Factors Handbook: 2011 Edition, Recommend Per Capita and Consumer-Only 

Values for Fish Intake (see Attachment 1 of this memorandum). EPA determined the model 

consumption rates for recreational and subsistence child cohorts based on values for finfish, 

excluding values for shellfish. The majority of steam electric discharges and those being 

modeled for the EA are fresh water bodies. EPA used the mean values for recreational fishers 

and 95th percentile values for subsistence fishers. Mean values are provided for both per capita5

and consumer-only6

 children. EPA used the per capita consumption rates for finfish. 

 To convert the data in the Exposure Factors Handbook to the correct units for the 

receiving water model (grams per day), EPA multiplied the listed consumption rate (grams per 

kilogram-day) by the mean body weight for each cohort as listed in Table 2-1 above [U.S. EPA, 

2008 Child-Specific Exposure Factor Handbook (EPA/600/R-06/096F) [DCN SE01876]]. Table 

2-2 shows the calculation of the consumption rates for use in the receiving water model. 

 The child recreational fisher consumption rates range between 2.5 to 7.2 grams per day. 

For comparison, the adult recreational fisher consumption rate is 20 grams per day. 

 

5

 Per capita intake rates are "generated by averaging consumer-only intakes of the entire survey population 

(including those individuals that reported no intake). In general, per capita intake rates are appropriate for use in 

exposure assessments for which average dose estimates are of interest." Reference: U.S. EPA Exposure Factors 

Handbook: 2011 Edition (EPA/600/R-09/052F) [DCN SE01912]. 

6

 Consumer-only intake refers to the "quantity of fish and shellfish consumed by individuals during the survey 

period." Reference: U.S. EPA Exposure Factors Handbook: 2011 Edition (EPA/600/R-09/052F) [DCN SE01912]. 
Memorandum 

April 19, 2013 Page 5 

Table 2-2. Calculation of Consumption Rates for Child Cohorts

Age Group 

(years)

Body Weight 

(mean), 

kg a

Recreational Subsistenc

Consumption Rate as a 

Factor of Body Weight 

(mean), 

g/kg-day b

Calculation of Consumption 

Rate for the Receiving Water 

Model (mean), 

g/day

Consumption Rate as a 

Factor of Body Weight 

(95th percentile), 

g/kg-day b

Calcula

Rate f

Mo

1 to <2 11.4 0.22 11.4 × 0.22 = 2.5 1.2 11.4 × 2 to <3 13.8 0.22 13.8 × 0.22 = 3 1.2 13.8 × 3 to <6 18.6 0.19 18.6 × 0.19 = 3.5 1.4 18.6 × 

6 to <11 31.8 0.16 31.8 × 0.16 = 5.1 1.1 31.8 × 

11 to <16 56.8 0.10 56.8 × 0.10 = 5.7 0.7 56.8 × 16 to <21 71.6 0.10 71.6 × 0.10 = 7.2 0.7 71.6 × 

Acronyms: kg (kilograms); g (grams). a – Table 8-1. Recommended Values for Body Weight, U.S. EPA 2008 Child-Specific Exposure Factor Handbook [EPA/600/R-06/096

(September) [DCN SE01876]. b – Table 10-1. Recommended Per Capita and Consumer-Only Values for Fish Intake (g/kg-day), Uncooked Fish: Per Capita for FinfisFactors Handbook: 2011 Edition [EPA/600/R-09/052F], Washington, DC. (September) [DCN SE01912].
Memorandum 

April 19, 2013 

Page 6 

Adult Cohorts – Recreational Fishers

 EPA determined consumption rates for adult recreational fishers using data from Table 

10-5 of the U.S. EPA Exposure Factors Handbook: 2011 Edition, Summary of Relevant Studies 

on Freshwater Recreational Fish Intake (see Attachment 1 of this memorandum). EPA used the 

mean values for freshwater fish consumption (g/day) based on location and population groups. 

EPA used consumption rates for all respondents and calculated a median value to use in the 

model. The Exposure Factors Handbook does not provide recommended values for fish 

consumption, but does present available data for certain geographic areas. Assessors may apply 

these data, if appropriate, to the scenarios and populations being assessed. EPA used the mean 

consumption rate across the geographic areas to represent a central-tendency value for adult 

fishers across the United States. A fraction of the adult fisher population may experience higher 

consumption rates as evidenced by the 95th percentile values presented in Table 10-5 of the U.S. 

EPA Exposure Factors Handbook: 2011 Edition. Table 2-3 shows the calculation of the adult 

recreational fisher consumption rate for use in the receiving water model. For the model, the 

adult recreational fisher consumption rate is 20 grams per day. For comparison, the adult 

subsistence fisher consumption rate is 88 grams per day. 

Adult Cohorts – Subsistence Fishers

 EPA determined consumption rates for adult subsistence fishers based on studies of 

Native American fish intake using data from Table 10-6 of the U.S. EPA Exposure Factors 

Handbook: 2011 Edition, Summary of Relevant Studies on Native American Fish Intake. EPA 

used the mean values for fish consumption based on location/name of Native American tribe. In 

some cases, studies looked at adults and adult consumers separately; however, the results did not 

vary significantly. EPA used values listed for adults and converted the data into consumption 

rates (units of g/day) assuming an adult body weight of 80 kilograms, as provided in Section 8.1 

of the U.S. EPA Exposure Factor Handbook: 2011 Edition. EPA then calculated a median value 

to use in the model. 

 As noted above, the Handbook does not provide recommended values for fish 

consumption but does present available data for certain geographic areas. Assessors may apply 

these data, if appropriate, to the scenarios and populations being assessed. EPA used the mean 

consumption rate across the geographic areas to represent a central-tendency value for adult 

fishers across the United States. A fraction of the adult fisher population may experience higher 

consumption rates as evidenced by the 95th percentile values presented in Table 10-6 of the U.S. 

EPA Exposure Factors Handbook: 2011 Edition. Table 2-4 shows the calculation of the adult 

recreational fisher consumption rate for use in the receiving water model. For the model, the 

adult recreational fisher consumption rate is 88 grams per day. 
Memorandum 

April 19, 2013 

Page 7 

Table 2-3. Calculation of Consumption Rates for Adult Recreational Cohort a

 

Location 

Population 

Group 

Mean Consumption Rate 

(g/day) 

Notes 

All 

Respondents

Consuming 

Anglers

Alabama Adults 44 53 Calculation: 83% of respondents were 

consumers. 

Connecticut Not specified a 51 53 Fresh and saltwater fish; Calculation: 97% of 

respondents were consumers. 

Georgia 

(Savannah River) 

Adults Values provided for two ethnic groups; table 

does not provide value for all adults. 

Indiana Not specified a 16 20 

Maine Not specified a 5 6.4 

Michigan Consuming 

anglers: 21 to 

80 years 

 16 Did not have value for "all" respondents. 

Minnesota Consuming 

anglers a

 14 Source lists 50th (and 95th) percentile for 0-14 

year olds; >14 years (male); 15 to 44 (female); 

and >44 (female). 

New York (Lake 

Ontario) 

Adults 4.9 5.8 Calculation: 84% of respondents were 

consumers. 

North Dakota Consuming 

anglers a

 12 Source lists 50th (and 95th) percentile for 0-14 

year olds; >14 years (male); 15 to 44 (female); 

and >44 (female). 

Tennessee 

(Clinch River) 

Not specified a 20 38 Consumption includes store-bought and selfcaught fish. 

Washington Adults 10 15 Calculation: 66% of respondents were 

consumers. 

Wisconsin Adults 11 12 

For All 

Respondents: 

 20.24 Range of mean values: 4.9 - 51 g/day; 

Median value is 13.5. 

For Consuming 

Anglers: 

 22.29 Range of mean values: 5.8 - 53 g/day; 

Median value is 15. 

Acronym: g (grams). 

a – Table 10-5. Summary of Relevant Studies on Freshwater Recreational Fish Intake, U.S. EPA Exposure Factors 

Handbook: 2011 Edition [EPA/600/R-09/052F], Washington, DC. (September) [DCN SE01912]. 
Memorandum 

April 19, 2013 Page 8 

Table 2-4. Calculation of Consumption Rates for Adult Subsistence Cohort a 

Location/ 

Tribe 

Population 

Group 

Consumption Rate 

Reported in Reference 

Consumption Rate, 

g/day b

No

Range or 95th 

Percentile Mean Units Range a Mean a

94 Alaska Communities 

All Respondents: Median of 94 a 16-770 81 g/day 16-770 81 

Chippewa Indians (Wisconsin) 

All Respondents: Adults N/A 39 g/day N/A 39 

4 Columbia River Tribes (Oregon) 

All Respondents: Adults 

≤170 59 g/day 

≤170 59 

Values also listed for chilConsumer adults (63 g/dadivided by 93% consumin

Florida All Respondents 

≤4.5 0.8 g/kg-day 

≤4.5 × 80 = 

≤360 64 Also have consumer-only 

uncooked fish weight). 

Minnesota All Respondents 

N/A 2.8 g/kg-day N/A 2.8 × 80 = 224 Also have consumer-only 

uncooked fish weight); meall respondents. 

Mowhawk Tribe (New York and Canada) 

All Respondents 

≤131 25 g/day 

≤131 25 

Values also listed for womwomen consumers (16 g/dyears), and consumers (adyear). 

North Dakota All Respondents 

≤0.9 0.4 g/kg-day 

≤0.9 × 80 = 

≤72 

0.4 × 80 = 

32 

Also have consumer-only same as all respondents. 

Tulalip Tribe (Washington) 

All Respondents: Adults 

≤2.9 0.9 g/kg-day 

≤2.9 × 80 = 

≤232 

0.9 × 80 = 

72 

Values also listed for chilconsumer adults (63 g/day

Squaxin Island Tribe (Washington) 

All Respondents: Adults 

≤3.0 0.9 g/kg-day 

≤3.0 × 80 = 

≤240 

0.9 × 80 = 

72 

Values also listed for chilfor consumers. Consumer g/kg-day.

Suquamish Tribe (Washington) 

All Respondents: Adults 

≤10 2.7 g/kg-day 

≤10.0 × 80 = 

≤800 

2.7 × 80 = 

216 

Values also listed for chilfor consumers. Consumer g/kg-day (same value as a

For All Tribes Listed: g/day 16 - 800 88 Range of mean values: 2

value is 68.

Acronyms: g (grams); kg (kilograms); N/A (not applicable). a – Table 10-6. Summary of Relevant Studies on Native American Fish Intake, U.S. EPA Exposure Factors Handbook: 2011 Edition [EPA/600/R-09/0

(September) [DCN SE01912]. b – If source reported results as grams per day, no change in value. If source reported results as grams per kilogram-day, multiplied by the mean adult 
Attachment 1 

April 19, 2013 

Page A-1 

Attachment 1: Excerpts from U.S. EPA Exposure Factors Handbook: 2011 Edition 
Attachment 1 

April 19, 2013 

Page A-2 
Attachment 1 

April 19, 2013 

Page A-3 
Attachment 1 

April 19, 2013 

Page A-4 
Attachment 1 

April 19, 2013 

Page A-5